Timing Advance Calculation for Non-Terrestrial Network Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In satellite-based communication systems, the long distances between user equipment (UE) and satellites result in significant and variable time delays, complicating signal transmission and reception due to the satellite's movement, which existing technologies struggle to accurately correct.
Innovation Solution
A method and device where the base station provides time offset information to the UE, allowing it to calculate and correct the time offset based on its location and the satellite's position, enabling precise timing adjustments for signal transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the UE transmits signals to/from a satellite through long distances, then coverage area is expanded, but time delay increases significantly
Solution Approach 1:
The base station performs preliminary calculations of the time offset based on satellite ephemeris data and UE location information before signal transmission. This pre-computed timing advance information is provided to the UE to proactively compensate for the long propagation delay, allowing the UE to transmit uplink signals at the correct timing without waiting for round-trip feedback.
2Area of stationary object
If the satellite moves to provide broad coverage, then coverage area is improved, but time delay becomes variable and harder to correct
Solution Approach 1:
The system dynamically updates the time offset information based on real-time satellite position changes. The base station continuously monitors satellite ephemeris data and recalculates the timing advance values as the satellite moves, ensuring that the UE receives current and accurate timing correction information that adapts to the changing geometric relationship between UE, satellite, and base station.
Solution Approach 2:
The system implements a feedback mechanism where the base station provides time offset information to the UE based on satellite position data, and the UE applies this correction to its uplink transmissions. The base station receives the corrected signals and can verify timing alignment, enabling continuous optimization of the timing advance values as the satellite moves across the sky.
3Measurement precision
If the UE calculates timing advance based on satellite position, then time offset correction is improved, but device complexity increases
Solution Approach 1:
The base station acts as an intermediary that performs the complex timing advance calculations on behalf of the UE. It receives satellite ephemeris data and UE location information, computes the appropriate time offset corrections, and provides these pre-calculated values to the UE. This shifts the computational burden from the resource-constrained UE to the more capable base station, simplifying the UE's task to merely applying the provided correction values.
Data Source
AI summary
An example method performed by a terminal in a non-terrestrial network (NTN) system may include receiving, from a base station, system information including position information about the base station and information about a common timing advance (TA) offset; determining the distance between the terminal and the base station based on the position information about the base station and position information about the terminal; determining a specific TA offset for the terminal based on the determined distance; determining a TA value on the basis of the common TA offset and the specific TA offset; determining the transmission start time point of a preamble based on the determined TA value; and transmitting the preamble to the base station based on the determined transmission start time point.